kk Blog —— 通用基础


date [-d @int|str] [+%s|"+%F %T"]
netstat -ltunp
sar -n DEV 1

SQL中case的使用方法

https://blog.csdn.net/m0_53222768/article/details/120101414

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SELECT CASE WHEN salary <= 500 THEN '1'
	WHEN salary > 500 AND salary <= 600  THEN '2'
	WHEN salary > 600 AND salary <= 800  THEN '3'
	WHEN salary > 800 AND salary <= 1000 THEN '4'
ELSE NULL END
salary_class,  COUNT(*)  FROM    Table_A
GROUP BY CASE WHEN salary <= 500 THEN '1'
	WHEN salary > 500 AND salary <= 600  THEN '2'
	WHEN salary > 600 AND salary <= 800  THEN '3'
	WHEN salary > 800 AND salary <= 1000 THEN '4'
ELSE NULL END;